Polyamides



Patented -Mar. 7,

Parr-na l? OFFICE POLYAMIDES Wallace n. Carothers,.Wllmington, net, mimito E. I. (in Pont'de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application January 1 3, 1937,

Serial No. 120,460

7 Claims. '(01. zed-2 This invention relates to a synthetic resin and more particularly to a new type of polyamide resin.

In my prior application Serial Number 548,701,

5 filed July 3, '1931, now Patent No. 2,071,250, I have described polyamides obtained by reacting diamines and dibasic acids. The polyamides so obtained are remarkable in that they may be formed into useful fibers showing by X-ray examination fiber orientation along the fiber axis.

These polyamides, however, are not heat-hardenable and are of limited solubility and are therefore of limited value in the. coating and molding arts. In order to obtain such fiberforming polymers it is necessary to use bifunctional reactants because, as I have observed in the above mentioned application, the presence of more than two functional groups (as would be the case if the diamine were replaced by a tri- 20 amine or the dibasic acid replaced by a tribasic acid) would result in a three-dimentional polyamide structure and not the linear fiber-forming polyamide with which the above mentioned application is concerned. The present invention, on

25 the other hand, relates specifically to the new and valuable resinous polyamides obtainable from polybasic acid and polyamine reactants, one of which is higher than bifunctional.

This invention has as an object the prepara- 80 tion of new and useful polymeric products. A further object is to make resinous polyamides of improved properties. A still further object is to prepare products useful in the plastic, molding, coating, sizing, adhesive, impregnating, and re- 35 lated arts. Other objects will appear hereinafter.

These objects are accomplished by heating under polymerizing conditions (generally from 100 to 300 C.) reactants comprising a polyamine and a saturated aliphatic non-imide-forming poly- 40 basic acid or amide-forming derivative thereof, at least one of said reactants being higher than bifunctional (i. e., the sum of the amide-forming groups in said reactants is at least five), until a resinous product is obtained.

45 It is to be understood that the mention herein of non-imide-forming polybasic acids includes the amide-forming derivatives of these acids, such as the ester, half ester, anhydride, acid halide, and amide, as well as the acids them- 50' selves. With reference to the minimum number of amide-forming groups, it will be seen that if a dibasic acid is used the amine must be at least a triamine or if a diamine is used the polycarboxylic acid must be at least a tricarboxylic acid I in order that the sum of the amide-forming groups, namely, amino and carboxyl, be at least five.

The polycarboxylic acids used in the practice of this invention are aliphatic and are non-imideforming, that is, they have little tendency to form imides from their amides when the latter are heated under conditions for resin formation. Phthalic' acid is unsuitable except in partial replacement of the aliphatic acidsince phthalic acid has a marked tendency toward cyclization or 'imide formation. Thus the reaction of phthalic 'anhydride withdiethylenetriamine leads to phthalimide formation which effectively blocks further polymerization and results in an acid soluble product of no value as a film-forming material. The dibasic acids having a radical length of five (the number of atoms in the chain between the two carboxyl groups plus the two carbon atoms of thecarboxyl groups, these acids having a chain of at least three atoms Joining the carboxyl groups), such as glutaric acid, and higher are in general valuable for the present purpose because of the little tendency of these acids in general to form imides. The preferred class of polybasic acids are the dicarboxylic acids having a radical length of at least six, or a chain of at least four atoms joining the carboxyl groups, such as adipic, since these acids have practically no tendency to form imides.

The term polyamine is used herein to indicate an organic amine containing at least two hydrogen-bearing nitrogen atoms, 1. e., primary or secondary amino groups. Thus, ethylenediamine, ,NHzCHzCHzNHz, contains two functional amino groups; diethylenetriamine,

NHzCHzCHzNHCHzCHzNI-Iz contains three functional amino groups; and triethylenetetramine,

NH2CH2CH2NHCH2CH2NHCH2CH2NH2 contains four functional amino groups. On the other hand, a compound of the formula NHaCHzCI-IzN (CH3) CH2CH2NH2 while it has three nitrogen atoms, contains only two functional amino groups.

The term aliphatic is used to indicate that the carboxyl groups of the polybasic acid are attached to aliphatic carbon atoms. It does not necessarily imply that the acid is an open chain compound, i. e., free from cyclic groups. Thus, many dibasic acids, e. g., diphenylolpropane diacetic acid, HOOCCH2OC15H14OCH2COOH, which contain an aromatic group but which have the carboxyl groups attached to aliphatic carbon atoms are useful particularly when employed in product melted at 235 C. 'and was soluble hr conjunction with open chain aliphatic polybasic acids.

The reaction for making the polyamides of this solvent, or in the presence of a non-solvent diluent. The reaction temperaturerequired to obpreferably 150-275 C. Derivatives ofthe polybasio acid, such as the ester or acid chloride, react more readily than the free acid. The .re-=

action by which the polymer is obtained is a condensation' polymerization, which involves the formationof a lay-product, such as water, alcohol, phenol, hydrogen chloride, or ammoniafdepending-upon the derivative'of the polybasic acid used. Generally, it is desirable to effect the reaction under conditions which permit the escape of the water or other by-products, but this is not absolutely essential. The reaction is preferably carried out in theabsence of air and sometimes the addition" of antioxidants is desirable. While it is usually unnecessary to add a catalyst, inorganic materials of alkaline reaction such as oxides and carbonates and acidic materials such "as halogen salts of polyvalent elements, e. g.,

aluminum or tin are often helpful. The reaction may be carried out in an open or closed reactor under atmospheric, super-atmospheric or sub-atmospheric pressures.

The following examples in which the parts are by weight are illustrative of my invention:

Example I A mixture of 13 parts of adiplc acid and 34.4 parts of diethylenetriamine was heated for 20 minutes at 220-225 C. under conditions which permitted the water formed in the reaction to distill out. The clear, light-yellow, resinous product thus obtained softened at about 50C. and was soluble in water and in various alcohols. It yielded transparent films. Continued heating converted the resin into an insoluble, infusible product.

Example II The salt prepared by adding an alcohol solution of 23.5 parts of adipic acid to a solution of 3 parts of diethylenetriamine, and 15.1 parts of hexamethylenediamine was heated with an equal weight of phenol for 1.5 hours,in a bath at 220- 225" C., allowing the water and'part of the phenol to distill out. Upon pouring the solution into an excess of ethyl acetate, a light-colored granular precipitate of polymer was formed. This phenol and in formic acid. The product proved useful 'in the preparation of films, sheets, and molded objects.

Example III A solution of 14.6 parts of triethylenetetramine in 50 parts of ethanol was added to a solution of 68.8 parts of diphenylolpropane diacetic acid in 200 parts of ethanol. The salt which crystallized from this mixture was heated 0.5 hour at 230 C. and then for 1.5 hours at 220 C. The resultant condensation product was a hard brown resin which had a softening point of about C. It; was soluble in the ethyl ether of ethylene glycol and in ethanol-benzene mixtures. Solutions of the resin were useful in the preparation of coating compositions.

The examples illustrate the preparation of preparations.

polya'mides from various polyamines and aliphatic non-imide-forming polybasic acids, at least one of said reactants being higher than blfunctional. As indicated in, Example II, it is possible to use more than. one polyamine in the preparationof a polyamide. It is also possible to use more than one polybaslc' acid. If the major portion of the ingredients are bifunctional it is possible to obtain products which approach in properties the fibereforming linear condensation polyamides described in the above men- .tioned application. As examples of additional polyaminesand polybasic acids which may be used in the preparation of-the products of this invention there may be mentioned ethylenediamine, tetramethylenediamine, pentamethylenediamine," octamethylenediamine, decamethylenediamine, p-xylylenediamine, di- (polymethylene).

- triamines (e. -g., di-(hexamethylene) triamine),

piperazine, tetramethyl piperazine, N-phenyl ethylenediamine, N-methyl ethylenediamine, N, N'-dimethyl ethylenediamine, glutaric acid, pi-

melic acid, suberic, azelaic acid, beta-methyl adipic acid, phenylene diacetic, resorcinol diacetic, camphorlc acid, dithioglycoloc acid, and

one of the polyfunctional reactants selected be higher thanwbifunctional. In general, it is desirable to uses. plyamine as the reactant higher than bifunctional.

In the preparation of the products of this invention it is .generally desirable to use the acids and amines in such proportions thatthe reactive amine and acid groups will be present in equimolecular amounts. Thus, if a triamine is reacted with a dibasic acid, the preferred proportions would be two moles of tria'mine and three of dibasic acid. In the examples given above the ratio of amine to'acid groups is such that there is substantially one amino group for each acid or acylating group.

The products of this invention are for the most part resins, whose softening point and solubility are dependent upon .the reactants used in their In gene'ral, the products are soluble in chlorinated hydrocarbons, esters, hydroxy ethers, phenols, formic acid, and mixtures of alcohols with aromatic hydrocarbons. In their initial state some of the products are soluble in water. On continued heating the products of this invention usually become insoluble, i. e., form three-dimensional polymers. For the most part; the products have good compatibility characteristics and can be admixed with drying oils, resins, plasticizers, and

.. in some instances with cellulose derivatives. It is sometimes desirable to prepare the polyamide in the presence of substances of this type. The above properties make the products useful in the coating, plastic, sizing, impregnating, adhesive, and related arts.

The reaction described'herein has also been a valuable addition to the coating art in that it has formed the basis for the manufacture of new products chemically modified with drying oils or oil acids, such as linseed, these improved products being the subject of the invention described in application Serial Number 120,459, filed of even date herewith by G. D. Graves. In accordance with this improvement it was found that the incorporation of materials containing the acid radical of a fatty oil (the fatty oil, the acids derived therefrom, or oil modified glyceryl phthalate resins) into the reaction mixture of the foregoing examples the resins obtained yield exceptionally tough and durable films. Resin acids, such as those of congo and rosin,-may also be used as modifying agents.

, As indicated above, this invention is capable of yielding valuable products of widely different properties depending upon the reactants selected for their preparation. The products, depending upon their properties, are useful in the coating, plastic, molding, sizing, impregnating, adhesive, textile, and related'arts. In these various applications the products may be mixed with one another or with other agents such as plasticizer, resins, cellulose derivatives, pigments, fillers,- dyes, and the like.

As many apparently widely different embodinients of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. A resinous film-forming polymer which comprises the reaction product of reactants consisting essentially of polyamine and polybasic acid, the polyamine having at least two amino nitrogen atomswhich are attached to aliphatic carbon atoms and which carry at least one hydrogen atom each, the polybasic acid being an aliphatic non-imide-forming polybasic carboxylic acid, of which two carboxyl groups are joined by a chainof at least three atoms, the

reactive amino groups and acid groups in said reactants being present in substantially equimolecular proportions and the sum of the amideforming groups in said reactants being at least five, said resinous polymer being identified by at least one of the characteristics consisting of insolubility with infusibility, and capability o 1 being converted upon heat treatment into the insoluble, infusible state.

It is hereby certified CERTIFICATE OF CORRECTION- 2. The polymer set forth in claim 1 in which said polyamine has at least three nitrogen atoms and said polybasic acid is a saturated aliphatic dibasic'acid having a chain of at least three atoms Joining the carboxyl groups.

3. The polymer set forth in claim 1 inwhich said polyamine comprises diamine and polyamine having at least three amino groups, and in which said polybasic acid is a saturated aliphatic non-imide-forming dibasic carboxylic acid having a chain of at least three atoms joining the carboxyl groups.

4. A process which comprises heating under polymerizing conditions until a resinous product is obtained reactants consisting essentially of polyamine and polybasic acid, the polyamine having at least two amino nitrogen atoms which are attached to aliphatic carbon atoms and which carry at least one hydrogen atom each, the polybasic acid being an aliphatic non-imideforming polybasic carboxylic acid of which two carboxyl groups are joined by a chain of at least three atoms, the reactive amino groups and acid groups in said reactants being in substantially equimolecular proportions and the sum of the -amide-forming groups in said reactants being at least five.

5. The process set forth in claim 4 in which the reaction is carried out in an inert solvent at a temperature of l-300 C.

6. The process set forth in claim 4 in which said polyamine has at least three nitrogen atoms WALLACE H- CAR," 0 :IL-i' March 7, 19 9.

WAILACE H. CAROTHERS. r v that error appears in the printed specification of the above numbered. patent requiring correction as follows: Page 1, first column, line 21, for "three-dimentional" readthree dimensional; page 2, first column, line 57, for "l5 parts' read T5 parts; line 59, for "220- "225 on! read. 220-225 0. {same page, second column, line 25, for "dithioglycoloc" read dighioglycolic; line 27, for the word "connection" read conjunction; line 55, for "plyamine 'read-po'lyamine; that the said Let- Z'ters Patent should be read with this, correction therein that the same may conform to the record of the case in the Patent pffice.

s ne and sealed h s 20th day for June, a. n. 1959 (Seal) u Henry ,-Va'n Arsdale Acting Commissioner of Patents. 

